There is currently a need for a lightweight, portable, emergency air supply particularly for aircraft crews who are subject to emergency egress from aircraft, particularly when such egress places such crews into water.
Breathing gas is highly pressurized and needs to be regulated from about 3,000 psi down to about 120 to 140 psi. Such regulators are known in self-contained breathing apparatus. Typically, pressure is reduced through two stages, with the second stage commonly referred to as a demand regulator. Inhalation from a demand regulator causes movement of a diaphragm which operates a valve linked to it. Upon the demand regulator valve opening, the first stage or high pressure regulator then regulates gas flow from the source, such as a high pressure tank or cylinder. For emergency use, such regulation of high pressure gas is also required.
In addition, it is desirable to quickly release the pressurized breathing gas under conditions which could cause overpressurization. In the past this has been solved by including a side passage separate from the gas flow passage which communicates with a high pressure zone having a plug inserted therein. The plug inserted in the side passage has an axial passage which is blocked by a burst disc, This additional side passage requires additional manufacturing operations and expense.